# TCP-Handhake with JVC

**URL:** <https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127>\
**Category:** General\
**Created:** [20 September 2020 20:18 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127 "2020-09-20T20:18:12Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![rustemg](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rustemg/32/25266_2.png) [@rustemg](https://discourse.nodered.org/u/rustemg)\
**Post date:** [20 September 2020 20:18 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/1 "2020-09-20T20:18:13Z")

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![1](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/d/8d9cbe48515a13edcf76f78b3fac8f038f5f9ffd.jpeg)  
Hello!  
I have projector D-Ila. I use a node "TCP request" (as here [TCP/IP 3 way handshake](https://discourse.nodered.org/t/tcp-ip-3-way-handshake/28059)) I'm trying to set up a connection. I manage to send the first command, but the connection remains open. This means that I can't start the pairing process again.  
Tried all the return options, messages are sent in the desired format only with setup "keep the connection open".  
But when I disable the node and deploy again, the process can start. Is it possible to start each command with the pairing process?  
This is a part of original manual. Thank you!

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**Author:** ![rustemg](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rustemg/32/25266_2.png) [@rustemg](https://discourse.nodered.org/u/rustemg)\
**Post date:** [20 September 2020 20:25 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/2 "2020-09-20T20:25:26Z")

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the problem is that the connection remains open, and each command must be accompanied by a handshake.  
Is there any way to force the connection to close before the next command?

 ![1](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/3/03a0e6a63562176d26e185d6230e331ab5374bec.jpeg)  
There is no reaction on inject node after first command

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [20 September 2020 21:35 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/3 "2020-09-20T21:35:10Z")

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The connection should be closed as soon as it has received the reply (unless set not to close - or not to wait for reply) - so either on timeout or after a certain number of characters.

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**Author:** ![rustemg](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rustemg/32/25266_2.png) [@rustemg](https://discourse.nodered.org/u/rustemg)\
**Post date:** [20 September 2020 21:44 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/4 "2020-09-20T21:44:49Z")

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unfortunately, if I close the connection, I will have to go through the pairing procedure again. After connecting, the projector asks "PJ\_OK", I answer" PJREQ", the projector answers" PJACK", then I send any command. Each response contains a different number of characters, and there are no other characteristics that would allow you to close by character. When I close by time, I get a response in the buffer only after closing the connection and it is unreadable

It would be great if you could immediately open a new connection through the same node.

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [20 September 2020 21:56 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/5 "2020-09-20T21:56:24Z")

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sorry - I'm not quite understanding the problem... you want to close the connection ? The spec says it will close automatically after 5 secs doesn't it ? Or you just need to keep sending some (maybe dummy) command every 4 secs to keep it alive ?  
Or maybe look at the tcp in and out pair of nodes instead.

What does the timed out buffer look like ? It may just have some extra control characters in that can be removed.

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**Author:** ![ristomatti](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ristomatti/32/5857_2.png) [@ristomatti](https://discourse.nodered.org/u/ristomatti)\
**Post date:** [20 September 2020 23:32 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/6 "2020-09-20T23:32:57Z")

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Is this by any chance about the same thing as topic [TCP/IP 3 way handshake](https://discourse.nodered.org/t/tcp-ip-3-way-handshake/28059)?

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [19 November 2020 23:33 UTC](https://discourse.nodered.org/t/tcp-handhake-with-jvc/33127/7 "2020-11-19T23:33:14Z")

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